Abstract
Background Hypoxia in the tumor microenvironment (TME) is often the main factor in the cancer progression. Moreover, low levels of oxygen in tumor tissue may signal that the first or second-line therapy will not be successful. This knowledge triggers the inevitable search for different kinds of treatment that will successfully cure aggressive tumors. Due to its exclusive expression on cancer cells, carbonic anhydrase IX belongs to the group of the most precise targets in hypoxic tumors. CA IX possesses several exceptional qualities that predetermine its crucial role in targeted therapy. Its expression on the cell membrane makes it an easily accessible target, while its absence in healthy corresponding tissues makes the treatment practically harmless. The presence of CA IX in solid tumors causes an acidic environment that may lead to the failure of standard therapy. Methods Parental mouse hybridomas (IV/18 and VII/20) were humanized to antibodies which were subsequently named CA9hu-1 and CA9hu-2. From each hybridoma we obtained 25 clones. Each clone was tested for ADCC and CDC activity, affinity, extracellular pH measurement, multicellular aggregation analysis and real-time monitoring of invasion with xCELLigence system. ResultsBoth CA9hu-1 and CA9hu-2 are IgG1 antibodies and they were both examined in vivo. Here we describe anti-CAIX antibodies that can reverse the failure of standard therapy as a result of an acidic environment by modulating the TME. CA9hu-1 is directed at the conformational epitope of the catalytic domain, while CA9hu-2 targets the sequential epitope of the proteo-glycan domain. They are both able to induce an immune response, have high affinity, as well as ADCC and CDC activity. While the first one internalizes after binding to the antigen, the second one is able to reduce metastases formation. More importantly, they have both proved the ability to block the acidification of the extracellular environment. ConclusionCA9hu-1 and CA9hu-2 are the very first humanized antibodies against CA IX that are likely to become suitable therapies for hypoxic tumors. These antibodies can be applied in the treatment therapy of primary tumors and suppression of metastases formation.
In vivo Molecular Prediction of Carbonic Anhydrase IX-G250MN Expression on Immunotherapy Outcome in Renal Cancer
